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jss06c6 · 04-14-2018

Here's the quick sequence..

1. removed FP1 fuse from fuse block
FP-1 Removed.jpg
2. started engine, let it run a bit to depressurize the system
3. disconnected battery
4. removed fuel fill cover (4 torx screws)
5. removed rubber fuel dam and disconnected fuel drain line
Drain Line Removed.jpg
6. removed white keeper key in plug
Wiring Plug Keeper.jpg
7. disconnected plug
8. removed fuel supply, return and vent hoses (took pliers and gently rotated hoses on pipe nipples to allow me to remove them
Fuel supply-return-vent-2.jpg
9. removed 10 mm bolts, being careful to capture the o-rings on each
10. carefully lifted the pump assembly, rotated it 90 degrees CCW and carefully worked it out of the tank (had to work the fuel hoses a bit to clear the lip of the tank
ZR-1 Fuel Pumps_Float 91 #473.jpg
11. removed the gasket (carefully to prevent any debris in the tank
12. was surprised to see a tray in the bottom of the tank where the float rests in an empty tank (it was yellow plastic)
13. taped the tank opening closed with duct tape to prevent contamination and debris from entering the tank

Once on the bench, I clipped one lead of my meter to the purple wiper lead on then sending unit and the other lead to ground. Tank empty read about 0.5 ohms, Tank full initially read 95 ohms. There was nothing erratic during a sweep from tank empty to tank full. I worked it multiple times slowly, then rapidly and the tank full reading moved to 105 ohms and was stable. I guess I might have had a little debris in the potentiometer. I could also see interference between the float rod and the fuel hose clamp to the top fuel pump. Don't believe this would cause a problem, but should not be hitting it regardless.

The socks looked pretty good for 27 years old. Tank was clean as well. My new pump assembly is backordered from Jegs.. Should ship on April 19th.. I'll compare the new to the old and install the new one. Not sure what I'll do quite yet with the old one since it still appears to be working..

So, at this point, I don't know what caused my fuel gauge to stick to essentially full for the first 60 miles.. Guess there was a small amount of debris, but likely would have cleared itself after a few more miles of driving.. Oh well, good to replace the pumps and sending unit as preventive maintenance.. I'll attach some photos for entertainment..

04-14-2018	#15
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: Fuel Sending Unit Here's the quick sequence.. 1. removed FP1 fuse from fuse block FP-1 Removed.jpg 2. started engine, let it run a bit to depressurize the system 3. disconnected battery 4. removed fuel fill cover (4 torx screws) 5. removed rubber fuel dam and disconnected fuel drain line Drain Line Removed.jpg 6. removed white keeper key in plug Wiring Plug Keeper.jpg 7. disconnected plug 8. removed fuel supply, return and vent hoses (took pliers and gently rotated hoses on pipe nipples to allow me to remove them Fuel supply-return-vent-2.jpg 9. removed 10 mm bolts, being careful to capture the o-rings on each 10. carefully lifted the pump assembly, rotated it 90 degrees CCW and carefully worked it out of the tank (had to work the fuel hoses a bit to clear the lip of the tank ZR-1 Fuel Pumps_Float 91 #473.jpg 11. removed the gasket (carefully to prevent any debris in the tank 12. was surprised to see a tray in the bottom of the tank where the float rests in an empty tank (it was yellow plastic) 13. taped the tank opening closed with duct tape to prevent contamination and debris from entering the tank Once on the bench, I clipped one lead of my meter to the purple wiper lead on then sending unit and the other lead to ground. Tank empty read about 0.5 ohms, Tank full initially read 95 ohms. There was nothing erratic during a sweep from tank empty to tank full. I worked it multiple times slowly, then rapidly and the tank full reading moved to 105 ohms and was stable. I guess I might have had a little debris in the potentiometer. I could also see interference between the float rod and the fuel hose clamp to the top fuel pump. Don't believe this would cause a problem, but should not be hitting it regardless. The socks looked pretty good for 27 years old. Tank was clean as well. My new pump assembly is backordered from Jegs.. Should ship on April 19th.. I'll compare the new to the old and install the new one. Not sure what I'll do quite yet with the old one since it still appears to be working.. So, at this point, I don't know what caused my fuel gauge to stick to essentially full for the first 60 miles.. Guess there was a small amount of debris, but likely would have cleared itself after a few more miles of driving.. Oh well, good to replace the pumps and sending unit as preventive maintenance.. I'll attach some photos for entertainment.. Last edited by jss06c6; 04-15-2018 at 10:40 PM.